A holographic stereogram is a type of hologram, characterized by having been made from a series of views, which are multiplexed into a single hologram. For a hologram having only horizontal parallax, a series of vertical strips is exposed. For a full parallax hologram, exposures in two orthogonal directions are used.
More specifically, the source data for holographic stereograms is a sequence of two-dimensional (2D) views. As compared to a “true” hologram, a physical object is not directly exposed. An example of a series of 2D views is a series of views taken with a motion controlled camera. Another example is a series of views generated by computer graphics software. The views may represent a scene that is still, or they may be continuous views of a scene in motion. However, there is no requirement that the views be all related to one scene.
Once the sequence of views is obtained, they are displayed using a spatial light modulator, such as film or a liquid crystal display. Appropriate optical processing is performed, and an object beam and a reference beam are used to expose holographic film. The result is a series of small component holograms which together form an integrated holographic image. Although the source material is two-dimensional, the viewer may perceive the holographic image to be three-dimensional.
Equipment for producing holograms tends to be expensive, complex, and large, and to require skilled operators. Hologram production has tended to be a labor intensive and time consuming process, with long lead times and limited opportunity for customization to the liking of an individual purchaser.